/* 修正 expression 抖动, 使 IE7- 在渲染前，先进行CSS的计算*/
* html {
    background-attachment: fixed;
    background-image: url(about:blank);
}

/* fixed for ie6 */
* html .overlay-mask {
    position: absolute;
    left: expression(eval('CSS1Compat' === document.compatMode ? document.documentElement.scrollLeft : document.body.scrollLeft));
    top: expression(eval('CSS1Compat' === document.compatMode ? document.documentElement.scrollTop : document.body.scrollTop));
}

html, body {
    margin: 0;
    padding: 0;
}

.overlay-mask {
    background-color: #000;
    opacity: .5;
    filter: alpha(opacity=50);
    /* inline */
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    position: fixed;
    -webkit-user-select: none;
}